1. Field of the invention:
This invention relates to an apparatus for successively transporting a photosensitive sheet from a roll of the sheet, the said apparatus being used in an apparatus for the formation of images utilizing the photosensitive sheet and an image-receiving sheet.
2. Description of the prior art:
In recent years, an apparatus for the formation of images which uses a photosensitive sheet coated with pressure-rupturable capsules containing chromogenic materials that are hardened when exposed to light and an image-receiving sheet coated with developing materials that react with the chromogenic materials to give rise to color images has been developed (Japanese Laid-Open Patent Publication No. 58-88739).
Such an apparatus comprises an apparatus for transporting a photosensitive sheet, in which the sheet is successively drawn out from a roll of the photosensitive sheet, and transported through a light-emitting section and a pressure-transfer section and then wound up around a take up rod. The photosensitive sheet is exposed to light reflected from an original at the above-mentioned light-emitting section. The light reflected from the original selectively illuminates the pressure-rupturable capsules on the photosensitive sheet so that some of the capsules are exposed to the light to be hardened and the others are not exposed to the light to be left unchanged, resulting in a latent image corresponding to the image of the original. The photosensitive sheet on which the latent image has been formed is then transported into the pressure-transfer section, where the photosensitive sheet is placed together with the image-receiving sheet and pressure is applied thereto. Thus, the pressure-rupturable capsules that have not been hardened rupture, and the chromogenic materials contained therein flow out and are transferred onto the image-receiving sheet. Then the chromogenic materials react with the developing materials coated on the image-receiving sheet, which gives rise to color in the chromogenic materials, thereby a colored image corresponding to the latent image being formed on the image-receiving sheet.
Japanese Laid-Open Patent Publication No. 61-24495 discloses the provision of a heating device for heating the image-receiving sheet on which the colored image has been formed, so as to enhance the reaction between the chromogenic materials and the developing materials, which makes the colored image glossy and more distinct. In general, such a heating device comprises a pair of heat rollers; that is, an upper roller including a heater therein and a lower roller pressed against the upper roller.
When the image-receiving sheet is heated by the upper heat roller including the heater, the chromogenic materials reacting with the developing materials on the sheet are softened, which may cause an offset, i.e., some of the chromogenic materials on the image-receiving sheet may adhere to the upper roller. Thus, the image-receiving sheet tends to stick to the upper roller due to the softened materials. When the latent image is formed up to the foremost portion of an image-forming area of the photosensitive sheet, the colored image is also formed up to the corresponding portion of the image-receiving sheet. In such a case, the foremost portion of the image-receiving sheet tends to stick to the upper roller due to the softened materials, which makes it difficult for the image-receiving sheet to be separated from the heat rollers. This interferes with the smooth operation of the whole apparatus for the formation of images.